Conventionally, this sort of vehicle air conditioning apparatus includes: a compressor driven by an engine as a power source of a vehicle; a radiator provided outside the vehicle interior; and a heat exchanger provided in the vehicle interior. With this vehicle air conditioning apparatus, a cooling operation is performed by: releasing the heat from the refrigerant discharged from the compressor in the radiator; absorbing the heat into the refrigerant in the heat exchanger; and supplying the air subjected to a heat exchange with the refrigerant in the heat exchanger to the vehicle interior. In addition, such a conventional vehicle air conditioning apparatus includes a heater core and perform a heating operation by: releasing the exhaust heat from the cooling water used to cool the engine in the heater core; and blowing the air subjected to a heat exchange with the cooling water in the heater core to the vehicle interior. Moreover, such a conventional vehicle air conditioning apparatus performs a heating and dehumidifying operation by: cooling the air to be supplied to the vehicle interior to a required absolute humidity in the heat exchanger for dehumidification; heating the cooled and dehumidified air in the heat exchanger to a desired temperature in the heater core; and blowing the heated air to the vehicle interior.
The above-mentioned vehicle air conditioning apparatus uses the exhaust heat from the engine as a heat source to heat the air for a heating operation, or a heating and dehumidifying operation. Generally, an electric car uses an electric motor as a power source, and it is difficult to acquire the exhaust heat that can heat the air by using the electric motor without an engine. Therefore, the above-mentioned vehicle air conditioning apparatus is not applicable to electric cars.
Therefore, there has been known a vehicle air conditioning apparatus applicable to an electric car that includes: a compressor configured to compress and discharge a refrigerant; a radiator provided in the vehicle interior and configured to release the heat from the refrigerant; a heat exchanger provided in the vehicle interior and configured to absorb the heat into the refrigerant and an outdoor heat exchanger provided outside the vehicle interior and configured to release the heat from the refrigerant or absorb the heat into the refrigerant (see, for example, Patent Literature 1). In this vehicle air conditioning apparatus, the refrigerant discharged from the compressor releases the heat in the heat exchanger, is decompressed by the expansion valve and absorbs the heat, so that the heating operation is performed. Meanwhile, in the vehicle air conditioning apparatus, the refrigerant discharged from the compressor releases the heat in the radiator, part of the refrigerant is decompressed by the expansion valve and absorbs the heat in the heat exchanger, and the remaining refrigerant is decompressed by the expansion valve and absorbs the heat in the outdoor heat exchanger, so that the heating and dehumidifying operation is performed.